Washington CNN  — 

President Donald Trump on Sunday tweeted another warning to Iranian leaders – “DO NOT KILL YOUR PROTESTERS” – as thousands of anti-government protesters gathered in Iran this weekend following Tehran’s admittance it mistakenly shot down a Ukrainian passenger jet, killing all 176 people on board.

“To the leaders of Iran - DO NOT KILL YOUR PROTESTERS. Thousands have already been killed or imprisoned by you, and the World is watching,” Trump wrote. “More importantly, the USA is watching. Turn your internet back on and let reporters roam free! Stop the killing of your great Iranian people!”

The tweet comes hours after the President voiced his administration’s support for the protesters, writing on Twitter that he has “stood” with them since he took office nearly three years ago.

“(A)nd my Administration will continue to stand with you. We are following your protests closely, and are inspired by your courage,” he tweeted in both English and Farsi.

In a separate tweet on Saturday, Trump wrote that Iran’s government “must allow human rights groups to monitor and report facts from the ground on the ongoing protests by the Iranian people.”

“There can not be another massacre of peaceful protesters, nor an internet shutdown. The world is watching,” Trump wrote.

Ukraine International Airlines Flight 752 crashed Wednesday after takeoff from Tehran’s airport. The crash came hours after Iran fired missiles at Iraqi military bases housing US troops in retaliation for a US drone strike at Baghdad airport that killed Iranian commander Qasem Soleimani.

Thousands of anti-government protesters gathered on Saturday outside the gates of Amir Kabir University, near the former US embassy in Tehran, to denounce the plane crash the government had blamed on human error and “US adventurism.”

In a video posted on social media, protesters chanted for Supreme Leader Ayatollah Ali Khamenei to step down and for those responsible for downing the plane to be prosecuted. “Death to the dictator,” some chanted. In one video, demonstrators chanted, “Khamenei have shame. Leave the country.”

US Secretary of State Mike Pompeo on Saturday tweeted, “The voice of the Iranian people is clear. They are fed up with the regime’s lies, corruption, ineptitude, and brutality of the IRGC under @khamenei_ir’s kleptocracy.”

“We stand with the Iranian people who deserve a better future,” Pompeo continued.

This story has been updated with additional comment from the President Sunday.

CNN’s Madeline Holcombe, Artemis Moshtaghian and Ray Sanchez contributed to this report.